</dl>
+ <note><title>How path substitutions are interpreted</title>
+ <p>Whether a path substitution is treated as a file-system path
+ or a URL-path depends on the context and whether it begins with
+ a slash:</p>
+ <ul>
+ <li><strong>Starts with <code>/</code>, server/vhost context:</strong>
+ Treated as a file-system path if the first path component exists
+ on disk; otherwise treated as a URL-path.</li>
+ <li><strong>Starts with <code>/</code>, per-directory context:</strong>
+ Always treated as a URL-path. No file-system guessing occurs.</li>
+ <li><strong>Does not start with <code>/</code> (relative),
+ server/vhost context:</strong> Treated as a URL-path relative
+ to the current request URI.</li>
+ <li><strong>Does not start with <code>/</code> (relative),
+ per-directory context:</strong> Treated as a URL-path relative
+ to the directory-path for which the <directive
+ module="core">Directory</directive> or <code>.htaccess</code>
+ applies. See <directive>RewriteBase</directive> for controlling
+ the prefix added to relative substitutions.</li>
+ </ul>
+ </note>
+
<p>In addition to plain text, the <em>Substitution</em> string can include</p>
<ol>